// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 1999 - 2008 Intel Corporation. */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/prefetch.h>
#include "ixgb.h"

char ixgb_driver_name[] = "ixgb";
static char ixgb_driver_string[] = "Intel(R) PRO/10GbE Network Driver";

#define DRIVERNAPI "-NAPI"
#define DRV_VERSION "1.0.135-k2" DRIVERNAPI
const char ixgb_driver_version[] = DRV_VERSION;
static const char ixgb_copyright[] = "Copyright (c) 1999-2008 Intel Corporation.";

#define IXGB_CB_LENGTH 256
static unsigned int copybreak __read_mostly = IXGB_CB_LENGTH;
module_param(copybreak, uint, 0644);
MODULE_PARM_DESC(copybreak,
        "Maximum size of packet that is copied to a new buffer on receive");

/* ixgb_pci_tbl - PCI Device ID Table
 *
 * Wildcard entries (PCI_ANY_ID) should come last
 * Last entry must be all 0s
 *
 * { Vendor ID, Device ID, SubVendor ID, SubDevice ID,
 *   Class, Class Mask, private data (not used) }
 */
static const struct pci_device_id ixgb_pci_tbl[] = {
        {PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX,
         PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
        {PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX_CX4,
         PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
        {PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX_SR,
         PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
        {PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX_LR,
         PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},

        /* required last entry */
        {0,}
};

MODULE_DEVICE_TABLE(pci, ixgb_pci_tbl);

/* Local Function Prototypes */
static int ixgb_init_module(void);
static void ixgb_exit_module(void);
static int ixgb_probe(struct pci_dev *pdev, const struct pci_device_id *ent);
static void ixgb_remove(struct pci_dev *pdev);
static int ixgb_sw_init(struct ixgb_adapter *adapter);
static int ixgb_open(struct net_device *netdev);
static int ixgb_close(struct net_device *netdev);
static void ixgb_configure_tx(struct ixgb_adapter *adapter);
static void ixgb_configure_rx(struct ixgb_adapter *adapter);
static void ixgb_setup_rctl(struct ixgb_adapter *adapter);
static void ixgb_clean_tx_ring(struct ixgb_adapter *adapter);
static void ixgb_clean_rx_ring(struct ixgb_adapter *adapter);
static void ixgb_set_multi(struct net_device *netdev);
static void ixgb_watchdog(struct timer_list *t);
static netdev_tx_t ixgb_xmit_frame(struct sk_buff *skb,
                                   struct net_device *netdev);
static int ixgb_change_mtu(struct net_device *netdev, int new_mtu);
static int ixgb_set_mac(struct net_device *netdev, void *p);
static irqreturn_t ixgb_intr(int irq, void *data);
static bool ixgb_clean_tx_irq(struct ixgb_adapter *adapter);

static int ixgb_clean(struct napi_struct *, int);
static bool ixgb_clean_rx_irq(struct ixgb_adapter *, int *, int);
static void ixgb_alloc_rx_buffers(struct ixgb_adapter *, int);

static void ixgb_tx_timeout(struct net_device *dev, unsigned int txqueue);
static void ixgb_tx_timeout_task(struct work_struct *work);

static void ixgb_vlan_strip_enable(struct ixgb_adapter *adapter);
static void ixgb_vlan_strip_disable(struct ixgb_adapter *adapter);
static int ixgb_vlan_rx_add_vid(struct net_device *netdev,
                                __be16 proto, u16 vid);
static int ixgb_vlan_rx_kill_vid(struct net_device *netdev,
                                 __be16 proto, u16 vid);
static void ixgb_restore_vlan(struct ixgb_adapter *adapter);

static pci_ers_result_t ixgb_io_error_detected (struct pci_dev *pdev,
                             enum pci_channel_state state);
static pci_ers_result_t ixgb_io_slot_reset (struct pci_dev *pdev);
static void ixgb_io_resume (struct pci_dev *pdev);

static const struct pci_error_handlers ixgb_err_handler = {
        .error_detected = ixgb_io_error_detected,
        .slot_reset = ixgb_io_slot_reset,
        .resume = ixgb_io_resume,
};

static struct pci_driver ixgb_driver = {
        .name     = ixgb_driver_name,
        .id_table = ixgb_pci_tbl,
        .probe    = ixgb_probe,
        .remove   = ixgb_remove,
        .err_handler = &ixgb_err_handler
};

MODULE_AUTHOR("Intel Corporation, <linux.nics@intel.com>");
MODULE_DESCRIPTION("Intel(R) PRO/10GbE Network Driver");
MODULE_LICENSE("GPL v2");
MODULE_VERSION(DRV_VERSION);

#define DEFAULT_MSG_ENABLE (NETIF_MSG_DRV|NETIF_MSG_PROBE|NETIF_MSG_LINK)
static int debug = -1;
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");

/**
 * ixgb_init_module - Driver Registration Routine
 *
 * ixgb_init_module is the first routine called when the driver is
 * loaded. All it does is register with the PCI subsystem.
 **/

static int __init
ixgb_init_module(void)
{
        pr_info("%s - version %s\n", ixgb_driver_string, ixgb_driver_version);
        pr_info("%s\n", ixgb_copyright);

        return pci_register_driver(&ixgb_driver);
}

module_init(ixgb_init_module);

/**
 * ixgb_exit_module - Driver Exit Cleanup Routine
 *
 * ixgb_exit_module is called just before the driver is removed
 * from memory.
 **/

static void __exit
ixgb_exit_module(void)
{
        pci_unregister_driver(&ixgb_driver);
}

module_exit(ixgb_exit_module);

/**
 * ixgb_irq_disable - Mask off interrupt generation on the NIC
 * @adapter: board private structure
 **/

static void
ixgb_irq_disable(struct ixgb_adapter *adapter)
{
        IXGB_WRITE_REG(&adapter->hw, IMC, ~0);
        IXGB_WRITE_FLUSH(&adapter->hw);
        synchronize_irq(adapter->pdev->irq);
}

/**
 * ixgb_irq_enable - Enable default interrupt generation settings
 * @adapter: board private structure
 **/

static void
ixgb_irq_enable(struct ixgb_adapter *adapter)
{
        u32 val = IXGB_INT_RXT0 | IXGB_INT_RXDMT0 |
                  IXGB_INT_TXDW | IXGB_INT_LSC;
        if (adapter->hw.subsystem_vendor_id == PCI_VENDOR_ID_SUN)
                val |= IXGB_INT_GPI0;
        IXGB_WRITE_REG(&adapter->hw, IMS, val);
        IXGB_WRITE_FLUSH(&adapter->hw);
}

int
ixgb_up(struct ixgb_adapter *adapter)
{
        struct net_device *netdev = adapter->netdev;
        int err, irq_flags = IRQF_SHARED;
        int max_frame = netdev->mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
        struct ixgb_hw *hw = &adapter->hw;

        /* hardware has been reset, we need to reload some things */

        ixgb_rar_set(hw, netdev->dev_addr, 0);
        ixgb_set_multi(netdev);

        ixgb_restore_vlan(adapter);

        ixgb_configure_tx(adapter);
        ixgb_setup_rctl(adapter);
        ixgb_configure_rx(adapter);
        ixgb_alloc_rx_buffers(adapter, IXGB_DESC_UNUSED(&adapter->rx_ring));

        /* disable interrupts and get the hardware into a known state */
        IXGB_WRITE_REG(&adapter->hw, IMC, 0xffffffff);

        /* only enable MSI if bus is in PCI-X mode */
        if (IXGB_READ_REG(&adapter->hw, STATUS) & IXGB_STATUS_PCIX_MODE) {
                err = pci_enable_msi(adapter->pdev);
                if (!err) {
                        adapter->have_msi = true;
                        irq_flags = 0;
                }
                /* proceed to try to request regular interrupt */
        }

        err = request_irq(adapter->pdev->irq, ixgb_intr, irq_flags,
                          netdev->name, netdev);
        if (err) {
                if (adapter->have_msi)
                        pci_disable_msi(adapter->pdev);
                netif_err(adapter, probe, adapter->netdev,
                          "Unable to allocate interrupt Error: %d\n", err);
                return err;
        }

        if ((hw->max_frame_size != max_frame) ||
                (hw->max_frame_size !=
                (IXGB_READ_REG(hw, MFS) >> IXGB_MFS_SHIFT))) {

                hw->max_frame_size = max_frame;

                IXGB_WRITE_REG(hw, MFS, hw->max_frame_size << IXGB_MFS_SHIFT);

                if (hw->max_frame_size >
                   IXGB_MAX_ENET_FRAME_SIZE_WITHOUT_FCS + ENET_FCS_LENGTH) {
                        u32 ctrl0 = IXGB_READ_REG(hw, CTRL0);

                        if (!(ctrl0 & IXGB_CTRL0_JFE)) {
                                ctrl0 |= IXGB_CTRL0_JFE;
                                IXGB_WRITE_REG(hw, CTRL0, ctrl0);
                        }
                }
        }

        clear_bit(__IXGB_DOWN, &adapter->flags);

        napi_enable(&adapter->napi);
        ixgb_irq_enable(adapter);

        netif_wake_queue(netdev);

        mod_timer(&adapter->watchdog_timer, jiffies);

        return 0;
}

void
ixgb_down(struct ixgb_adapter *adapter, bool kill_watchdog)
{
        struct net_device *netdev = adapter->netdev;

        /* prevent the interrupt handler from restarting watchdog */
        set_bit(__IXGB_DOWN, &adapter->flags);

        netif_carrier_off(netdev);

        napi_disable(&adapter->napi);
        /* waiting for NAPI to complete can re-enable interrupts */
        ixgb_irq_disable(adapter);
        free_irq(adapter->pdev->irq, netdev);

        if (adapter->have_msi)
                pci_disable_msi(adapter->pdev);

        if (kill_watchdog)
                del_timer_sync(&adapter->watchdog_timer);

        adapter->link_speed = 0;
        adapter->link_duplex = 0;
        netif_stop_queue(netdev);

        ixgb_reset(adapter);
        ixgb_clean_tx_ring(adapter);
        ixgb_clean_rx_ring(adapter);
}

void
ixgb_reset(struct ixgb_adapter *adapter)
{
        struct ixgb_hw *hw = &adapter->hw;

        ixgb_adapter_stop(hw);
        if (!ixgb_init_hw(hw))
                netif_err(adapter, probe, adapter->netdev, "ixgb_init_hw failed\n");

        /* restore frame size information */
        IXGB_WRITE_REG(hw, MFS, hw->max_frame_size << IXGB_MFS_SHIFT);
        if (hw->max_frame_size >
            IXGB_MAX_ENET_FRAME_SIZE_WITHOUT_FCS + ENET_FCS_LENGTH) {
                u32 ctrl0 = IXGB_READ_REG(hw, CTRL0);
                if (!(ctrl0 & IXGB_CTRL0_JFE)) {
                        ctrl0 |= IXGB_CTRL0_JFE;
                        IXGB_WRITE_REG(hw, CTRL0, ctrl0);
                }
        }
}

static netdev_features_t
ixgb_fix_features(struct net_device *netdev, netdev_features_t features)
{
        /*
         * Tx VLAN insertion does not work per HW design when Rx stripping is
         * disabled.
         */
        if (!(features & NETIF_F_HW_VLAN_CTAG_RX))
                features &= ~NETIF_F_HW_VLAN_CTAG_TX;

        return features;
}

static int
ixgb_set_features(struct net_device *netdev, netdev_features_t features)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        netdev_features_t changed = features ^ netdev->features;

        if (!(changed & (NETIF_F_RXCSUM|NETIF_F_HW_VLAN_CTAG_RX)))
                return 0;

        adapter->rx_csum = !!(features & NETIF_F_RXCSUM);

        if (netif_running(netdev)) {
                ixgb_down(adapter, true);
                ixgb_up(adapter);
                ixgb_set_speed_duplex(netdev);
        } else
                ixgb_reset(adapter);

        return 0;
}


static const struct net_device_ops ixgb_netdev_ops = {
        .ndo_open               = ixgb_open,
        .ndo_stop               = ixgb_close,
        .ndo_start_xmit         = ixgb_xmit_frame,
        .ndo_set_rx_mode        = ixgb_set_multi,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_set_mac_address    = ixgb_set_mac,
        .ndo_change_mtu         = ixgb_change_mtu,
        .ndo_tx_timeout         = ixgb_tx_timeout,
        .ndo_vlan_rx_add_vid    = ixgb_vlan_rx_add_vid,
        .ndo_vlan_rx_kill_vid   = ixgb_vlan_rx_kill_vid,
        .ndo_fix_features       = ixgb_fix_features,
        .ndo_set_features       = ixgb_set_features,
};

/**
 * ixgb_probe - Device Initialization Routine
 * @pdev: PCI device information struct
 * @ent: entry in ixgb_pci_tbl
 *
 * Returns 0 on success, negative on failure
 *
 * ixgb_probe initializes an adapter identified by a pci_dev structure.
 * The OS initialization, configuring of the adapter private structure,
 * and a hardware reset occur.
 **/

static int
ixgb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
        struct net_device *netdev = NULL;
        struct ixgb_adapter *adapter;
        static int cards_found = 0;
        int pci_using_dac;
        int i;
        int err;

        err = pci_enable_device(pdev);
        if (err)
                return err;

        pci_using_dac = 0;
        err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
        if (!err) {
                pci_using_dac = 1;
        } else {
                err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
                if (err) {
                        pr_err("No usable DMA configuration, aborting\n");
                        goto err_dma_mask;
                }
        }

        err = pci_request_regions(pdev, ixgb_driver_name);
        if (err)
                goto err_request_regions;

        pci_set_master(pdev);

        netdev = alloc_etherdev(sizeof(struct ixgb_adapter));
        if (!netdev) {
                err = -ENOMEM;
                goto err_alloc_etherdev;
        }

        SET_NETDEV_DEV(netdev, &pdev->dev);

        pci_set_drvdata(pdev, netdev);
        adapter = netdev_priv(netdev);
        adapter->netdev = netdev;
        adapter->pdev = pdev;
        adapter->hw.back = adapter;
        adapter->msg_enable = netif_msg_init(debug, DEFAULT_MSG_ENABLE);

        adapter->hw.hw_addr = pci_ioremap_bar(pdev, BAR_0);
        if (!adapter->hw.hw_addr) {
                err = -EIO;
                goto err_ioremap;
        }

        for (i = BAR_1; i < PCI_STD_NUM_BARS; i++) {
                if (pci_resource_len(pdev, i) == 0)
                        continue;
                if (pci_resource_flags(pdev, i) & IORESOURCE_IO) {
                        adapter->hw.io_base = pci_resource_start(pdev, i);
                        break;
                }
        }

        netdev->netdev_ops = &ixgb_netdev_ops;
        ixgb_set_ethtool_ops(netdev);
        netdev->watchdog_timeo = 5 * HZ;
        netif_napi_add(netdev, &adapter->napi, ixgb_clean, 64);

        strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);

        adapter->bd_number = cards_found;
        adapter->link_speed = 0;
        adapter->link_duplex = 0;

        /* setup the private structure */

        err = ixgb_sw_init(adapter);
        if (err)
                goto err_sw_init;

        netdev->hw_features = NETIF_F_SG |
                           NETIF_F_TSO |
                           NETIF_F_HW_CSUM |
                           NETIF_F_HW_VLAN_CTAG_TX |
                           NETIF_F_HW_VLAN_CTAG_RX;
        netdev->features = netdev->hw_features |
                           NETIF_F_HW_VLAN_CTAG_FILTER;
        netdev->hw_features |= NETIF_F_RXCSUM;

        if (pci_using_dac) {
                netdev->features |= NETIF_F_HIGHDMA;
                netdev->vlan_features |= NETIF_F_HIGHDMA;
        }

        /* MTU range: 68 - 16114 */
        netdev->min_mtu = ETH_MIN_MTU;
        netdev->max_mtu = IXGB_MAX_JUMBO_FRAME_SIZE - ETH_HLEN;

        /* make sure the EEPROM is good */

        if (!ixgb_validate_eeprom_checksum(&adapter->hw)) {
                netif_err(adapter, probe, adapter->netdev,
                          "The EEPROM Checksum Is Not Valid\n");
                err = -EIO;
                goto err_eeprom;
        }

        ixgb_get_ee_mac_addr(&adapter->hw, netdev->dev_addr);

        if (!is_valid_ether_addr(netdev->dev_addr)) {
                netif_err(adapter, probe, adapter->netdev, "Invalid MAC Address\n");
                err = -EIO;
                goto err_eeprom;
        }

        adapter->part_num = ixgb_get_ee_pba_number(&adapter->hw);

        timer_setup(&adapter->watchdog_timer, ixgb_watchdog, 0);

        INIT_WORK(&adapter->tx_timeout_task, ixgb_tx_timeout_task);

        strcpy(netdev->name, "eth%d");
        err = register_netdev(netdev);
        if (err)
                goto err_register;

        /* carrier off reporting is important to ethtool even BEFORE open */
        netif_carrier_off(netdev);

        netif_info(adapter, probe, adapter->netdev,
                   "Intel(R) PRO/10GbE Network Connection\n");
        ixgb_check_options(adapter);
        /* reset the hardware with the new settings */

        ixgb_reset(adapter);

        cards_found++;
        return 0;

err_register:
err_sw_init:
err_eeprom:
        iounmap(adapter->hw.hw_addr);
err_ioremap:
        free_netdev(netdev);
err_alloc_etherdev:
        pci_release_regions(pdev);
err_request_regions:
err_dma_mask:
        pci_disable_device(pdev);
        return err;
}

/**
 * ixgb_remove - Device Removal Routine
 * @pdev: PCI device information struct
 *
 * ixgb_remove is called by the PCI subsystem to alert the driver
 * that it should release a PCI device.  The could be caused by a
 * Hot-Plug event, or because the driver is going to be removed from
 * memory.
 **/

static void
ixgb_remove(struct pci_dev *pdev)
{
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct ixgb_adapter *adapter = netdev_priv(netdev);

        cancel_work_sync(&adapter->tx_timeout_task);

        unregister_netdev(netdev);

        iounmap(adapter->hw.hw_addr);
        pci_release_regions(pdev);

        free_netdev(netdev);
        pci_disable_device(pdev);
}

/**
 * ixgb_sw_init - Initialize general software structures (struct ixgb_adapter)
 * @adapter: board private structure to initialize
 *
 * ixgb_sw_init initializes the Adapter private data structure.
 * Fields are initialized based on PCI device information and
 * OS network device settings (MTU size).
 **/

static int
ixgb_sw_init(struct ixgb_adapter *adapter)
{
        struct ixgb_hw *hw = &adapter->hw;
        struct net_device *netdev = adapter->netdev;
        struct pci_dev *pdev = adapter->pdev;

        /* PCI config space info */

        hw->vendor_id = pdev->vendor;
        hw->device_id = pdev->device;
        hw->subsystem_vendor_id = pdev->subsystem_vendor;
        hw->subsystem_id = pdev->subsystem_device;

        hw->max_frame_size = netdev->mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
        adapter->rx_buffer_len = hw->max_frame_size + 8; /* + 8 for errata */

        if ((hw->device_id == IXGB_DEVICE_ID_82597EX) ||
            (hw->device_id == IXGB_DEVICE_ID_82597EX_CX4) ||
            (hw->device_id == IXGB_DEVICE_ID_82597EX_LR) ||
            (hw->device_id == IXGB_DEVICE_ID_82597EX_SR))
                hw->mac_type = ixgb_82597;
        else {
                /* should never have loaded on this device */
                netif_err(adapter, probe, adapter->netdev, "unsupported device id\n");
        }

        /* enable flow control to be programmed */
        hw->fc.send_xon = 1;

        set_bit(__IXGB_DOWN, &adapter->flags);
        return 0;
}

/**
 * ixgb_open - Called when a network interface is made active
 * @netdev: network interface device structure
 *
 * Returns 0 on success, negative value on failure
 *
 * The open entry point is called when a network interface is made
 * active by the system (IFF_UP).  At this point all resources needed
 * for transmit and receive operations are allocated, the interrupt
 * handler is registered with the OS, the watchdog timer is started,
 * and the stack is notified that the interface is ready.
 **/

static int
ixgb_open(struct net_device *netdev)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        int err;

        /* allocate transmit descriptors */
        err = ixgb_setup_tx_resources(adapter);
        if (err)
                goto err_setup_tx;

        netif_carrier_off(netdev);

        /* allocate receive descriptors */

        err = ixgb_setup_rx_resources(adapter);
        if (err)
                goto err_setup_rx;

        err = ixgb_up(adapter);
        if (err)
                goto err_up;

        netif_start_queue(netdev);

        return 0;

err_up:
        ixgb_free_rx_resources(adapter);
err_setup_rx:
        ixgb_free_tx_resources(adapter);
err_setup_tx:
        ixgb_reset(adapter);

        return err;
}

/**
 * ixgb_close - Disables a network interface
 * @netdev: network interface device structure
 *
 * Returns 0, this is not allowed to fail
 *
 * The close entry point is called when an interface is de-activated
 * by the OS.  The hardware is still under the drivers control, but
 * needs to be disabled.  A global MAC reset is issued to stop the
 * hardware, and all transmit and receive resources are freed.
 **/

static int
ixgb_close(struct net_device *netdev)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);

        ixgb_down(adapter, true);

        ixgb_free_tx_resources(adapter);
        ixgb_free_rx_resources(adapter);

        return 0;
}

/**
 * ixgb_setup_tx_resources - allocate Tx resources (Descriptors)
 * @adapter: board private structure
 *
 * Return 0 on success, negative on failure
 **/

int
ixgb_setup_tx_resources(struct ixgb_adapter *adapter)
{
        struct ixgb_desc_ring *txdr = &adapter->tx_ring;
        struct pci_dev *pdev = adapter->pdev;
        int size;

        size = sizeof(struct ixgb_buffer) * txdr->count;
        txdr->buffer_info = vzalloc(size);
        if (!txdr->buffer_info)
                return -ENOMEM;

        /* round up to nearest 4K */

        txdr->size = txdr->count * sizeof(struct ixgb_tx_desc);
        txdr->size = ALIGN(txdr->size, 4096);

        txdr->desc = dma_alloc_coherent(&pdev->dev, txdr->size, &txdr->dma,
                                        GFP_KERNEL);
        if (!txdr->desc) {
                vfree(txdr->buffer_info);
                return -ENOMEM;
        }

        txdr->next_to_use = 0;
        txdr->next_to_clean = 0;

        return 0;
}

/**
 * ixgb_configure_tx - Configure 82597 Transmit Unit after Reset.
 * @adapter: board private structure
 *
 * Configure the Tx unit of the MAC after a reset.
 **/

static void
ixgb_configure_tx(struct ixgb_adapter *adapter)
{
        u64 tdba = adapter->tx_ring.dma;
        u32 tdlen = adapter->tx_ring.count * sizeof(struct ixgb_tx_desc);
        u32 tctl;
        struct ixgb_hw *hw = &adapter->hw;

        /* Setup the Base and Length of the Tx Descriptor Ring
         * tx_ring.dma can be either a 32 or 64 bit value
         */

        IXGB_WRITE_REG(hw, TDBAL, (tdba & 0x00000000ffffffffULL));
        IXGB_WRITE_REG(hw, TDBAH, (tdba >> 32));

        IXGB_WRITE_REG(hw, TDLEN, tdlen);

        /* Setup the HW Tx Head and Tail descriptor pointers */

        IXGB_WRITE_REG(hw, TDH, 0);
        IXGB_WRITE_REG(hw, TDT, 0);

        /* don't set up txdctl, it induces performance problems if configured
         * incorrectly */
        /* Set the Tx Interrupt Delay register */

        IXGB_WRITE_REG(hw, TIDV, adapter->tx_int_delay);

        /* Program the Transmit Control Register */

        tctl = IXGB_TCTL_TCE | IXGB_TCTL_TXEN | IXGB_TCTL_TPDE;
        IXGB_WRITE_REG(hw, TCTL, tctl);

        /* Setup Transmit Descriptor Settings for this adapter */
        adapter->tx_cmd_type =
                IXGB_TX_DESC_TYPE |
                (adapter->tx_int_delay_enable ? IXGB_TX_DESC_CMD_IDE : 0);
}

/**
 * ixgb_setup_rx_resources - allocate Rx resources (Descriptors)
 * @adapter: board private structure
 *
 * Returns 0 on success, negative on failure
 **/

int
ixgb_setup_rx_resources(struct ixgb_adapter *adapter)
{
        struct ixgb_desc_ring *rxdr = &adapter->rx_ring;
        struct pci_dev *pdev = adapter->pdev;
        int size;

        size = sizeof(struct ixgb_buffer) * rxdr->count;
        rxdr->buffer_info = vzalloc(size);
        if (!rxdr->buffer_info)
                return -ENOMEM;

        /* Round up to nearest 4K */

        rxdr->size = rxdr->count * sizeof(struct ixgb_rx_desc);
        rxdr->size = ALIGN(rxdr->size, 4096);

        rxdr->desc = dma_alloc_coherent(&pdev->dev, rxdr->size, &rxdr->dma,
                                        GFP_KERNEL);

        if (!rxdr->desc) {
                vfree(rxdr->buffer_info);
                return -ENOMEM;
        }

        rxdr->next_to_clean = 0;
        rxdr->next_to_use = 0;

        return 0;
}

/**
 * ixgb_setup_rctl - configure the receive control register
 * @adapter: Board private structure
 **/

static void
ixgb_setup_rctl(struct ixgb_adapter *adapter)
{
        u32 rctl;

        rctl = IXGB_READ_REG(&adapter->hw, RCTL);

        rctl &= ~(3 << IXGB_RCTL_MO_SHIFT);

        rctl |=
                IXGB_RCTL_BAM | IXGB_RCTL_RDMTS_1_2 |
                IXGB_RCTL_RXEN | IXGB_RCTL_CFF |
                (adapter->hw.mc_filter_type << IXGB_RCTL_MO_SHIFT);

        rctl |= IXGB_RCTL_SECRC;

        if (adapter->rx_buffer_len <= IXGB_RXBUFFER_2048)
                rctl |= IXGB_RCTL_BSIZE_2048;
        else if (adapter->rx_buffer_len <= IXGB_RXBUFFER_4096)
                rctl |= IXGB_RCTL_BSIZE_4096;
        else if (adapter->rx_buffer_len <= IXGB_RXBUFFER_8192)
                rctl |= IXGB_RCTL_BSIZE_8192;
        else if (adapter->rx_buffer_len <= IXGB_RXBUFFER_16384)
                rctl |= IXGB_RCTL_BSIZE_16384;

        IXGB_WRITE_REG(&adapter->hw, RCTL, rctl);
}

/**
 * ixgb_configure_rx - Configure 82597 Receive Unit after Reset.
 * @adapter: board private structure
 *
 * Configure the Rx unit of the MAC after a reset.
 **/

static void
ixgb_configure_rx(struct ixgb_adapter *adapter)
{
        u64 rdba = adapter->rx_ring.dma;
        u32 rdlen = adapter->rx_ring.count * sizeof(struct ixgb_rx_desc);
        struct ixgb_hw *hw = &adapter->hw;
        u32 rctl;
        u32 rxcsum;

        /* make sure receives are disabled while setting up the descriptors */

        rctl = IXGB_READ_REG(hw, RCTL);
        IXGB_WRITE_REG(hw, RCTL, rctl & ~IXGB_RCTL_RXEN);

        /* set the Receive Delay Timer Register */

        IXGB_WRITE_REG(hw, RDTR, adapter->rx_int_delay);

        /* Setup the Base and Length of the Rx Descriptor Ring */

        IXGB_WRITE_REG(hw, RDBAL, (rdba & 0x00000000ffffffffULL));
        IXGB_WRITE_REG(hw, RDBAH, (rdba >> 32));

        IXGB_WRITE_REG(hw, RDLEN, rdlen);

        /* Setup the HW Rx Head and Tail Descriptor Pointers */
        IXGB_WRITE_REG(hw, RDH, 0);
        IXGB_WRITE_REG(hw, RDT, 0);

        /* due to the hardware errata with RXDCTL, we are unable to use any of
         * the performance enhancing features of it without causing other
         * subtle bugs, some of the bugs could include receive length
         * corruption at high data rates (WTHRESH > 0) and/or receive
         * descriptor ring irregularites (particularly in hardware cache) */
        IXGB_WRITE_REG(hw, RXDCTL, 0);

        /* Enable Receive Checksum Offload for TCP and UDP */
        if (adapter->rx_csum) {
                rxcsum = IXGB_READ_REG(hw, RXCSUM);
                rxcsum |= IXGB_RXCSUM_TUOFL;
                IXGB_WRITE_REG(hw, RXCSUM, rxcsum);
        }

        /* Enable Receives */

        IXGB_WRITE_REG(hw, RCTL, rctl);
}

/**
 * ixgb_free_tx_resources - Free Tx Resources
 * @adapter: board private structure
 *
 * Free all transmit software resources
 **/

void
ixgb_free_tx_resources(struct ixgb_adapter *adapter)
{
        struct pci_dev *pdev = adapter->pdev;

        ixgb_clean_tx_ring(adapter);

        vfree(adapter->tx_ring.buffer_info);
        adapter->tx_ring.buffer_info = NULL;

        dma_free_coherent(&pdev->dev, adapter->tx_ring.size,
                          adapter->tx_ring.desc, adapter->tx_ring.dma);

        adapter->tx_ring.desc = NULL;
}

static void
ixgb_unmap_and_free_tx_resource(struct ixgb_adapter *adapter,
                                struct ixgb_buffer *buffer_info)
{
        if (buffer_info->dma) {
                if (buffer_info->mapped_as_page)
                        dma_unmap_page(&adapter->pdev->dev, buffer_info->dma,
                                       buffer_info->length, DMA_TO_DEVICE);
                else
                        dma_unmap_single(&adapter->pdev->dev, buffer_info->dma,
                                         buffer_info->length, DMA_TO_DEVICE);
                buffer_info->dma = 0;
        }

        if (buffer_info->skb) {
                dev_kfree_skb_any(buffer_info->skb);
                buffer_info->skb = NULL;
        }
        buffer_info->time_stamp = 0;
        /* these fields must always be initialized in tx
         * buffer_info->length = 0;
         * buffer_info->next_to_watch = 0; */
}

/**
 * ixgb_clean_tx_ring - Free Tx Buffers
 * @adapter: board private structure
 **/

static void
ixgb_clean_tx_ring(struct ixgb_adapter *adapter)
{
        struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
        struct ixgb_buffer *buffer_info;
        unsigned long size;
        unsigned int i;

        /* Free all the Tx ring sk_buffs */

        for (i = 0; i < tx_ring->count; i++) {
                buffer_info = &tx_ring->buffer_info[i];
                ixgb_unmap_and_free_tx_resource(adapter, buffer_info);
        }

        size = sizeof(struct ixgb_buffer) * tx_ring->count;
        memset(tx_ring->buffer_info, 0, size);

        /* Zero out the descriptor ring */

        memset(tx_ring->desc, 0, tx_ring->size);

        tx_ring->next_to_use = 0;
        tx_ring->next_to_clean = 0;

        IXGB_WRITE_REG(&adapter->hw, TDH, 0);
        IXGB_WRITE_REG(&adapter->hw, TDT, 0);
}

/**
 * ixgb_free_rx_resources - Free Rx Resources
 * @adapter: board private structure
 *
 * Free all receive software resources
 **/

void
ixgb_free_rx_resources(struct ixgb_adapter *adapter)
{
        struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
        struct pci_dev *pdev = adapter->pdev;

        ixgb_clean_rx_ring(adapter);

        vfree(rx_ring->buffer_info);
        rx_ring->buffer_info = NULL;

        dma_free_coherent(&pdev->dev, rx_ring->size, rx_ring->desc,
                          rx_ring->dma);

        rx_ring->desc = NULL;
}

/**
 * ixgb_clean_rx_ring - Free Rx Buffers
 * @adapter: board private structure
 **/

static void
ixgb_clean_rx_ring(struct ixgb_adapter *adapter)
{
        struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
        struct ixgb_buffer *buffer_info;
        struct pci_dev *pdev = adapter->pdev;
        unsigned long size;
        unsigned int i;

        /* Free all the Rx ring sk_buffs */

        for (i = 0; i < rx_ring->count; i++) {
                buffer_info = &rx_ring->buffer_info[i];
                if (buffer_info->dma) {
                        dma_unmap_single(&pdev->dev,
                                         buffer_info->dma,
                                         buffer_info->length,
                                         DMA_FROM_DEVICE);
                        buffer_info->dma = 0;
                        buffer_info->length = 0;
                }

                if (buffer_info->skb) {

                        dev_kfree_skb(buffer_info->skb);
                        buffer_info->skb = NULL;
                }
        }

        size = sizeof(struct ixgb_buffer) * rx_ring->count;
        memset(rx_ring->buffer_info, 0, size);

        /* Zero out the descriptor ring */

        memset(rx_ring->desc, 0, rx_ring->size);

        rx_ring->next_to_clean = 0;
        rx_ring->next_to_use = 0;

        IXGB_WRITE_REG(&adapter->hw, RDH, 0);
        IXGB_WRITE_REG(&adapter->hw, RDT, 0);
}

/**
 * ixgb_set_mac - Change the Ethernet Address of the NIC
 * @netdev: network interface device structure
 * @p: pointer to an address structure
 *
 * Returns 0 on success, negative on failure
 **/

static int
ixgb_set_mac(struct net_device *netdev, void *p)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        struct sockaddr *addr = p;

        if (!is_valid_ether_addr(addr->sa_data))
                return -EADDRNOTAVAIL;

        memcpy(netdev->dev_addr, addr->sa_data, netdev->addr_len);

        ixgb_rar_set(&adapter->hw, addr->sa_data, 0);

        return 0;
}

/**
 * ixgb_set_multi - Multicast and Promiscuous mode set
 * @netdev: network interface device structure
 *
 * The set_multi entry point is called whenever the multicast address
 * list or the network interface flags are updated.  This routine is
 * responsible for configuring the hardware for proper multicast,
 * promiscuous mode, and all-multi behavior.
 **/

static void
ixgb_set_multi(struct net_device *netdev)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        struct ixgb_hw *hw = &adapter->hw;
        struct netdev_hw_addr *ha;
        u32 rctl;

        /* Check for Promiscuous and All Multicast modes */

        rctl = IXGB_READ_REG(hw, RCTL);

        if (netdev->flags & IFF_PROMISC) {
                rctl |= (IXGB_RCTL_UPE | IXGB_RCTL_MPE);
                /* disable VLAN filtering */
                rctl &= ~IXGB_RCTL_CFIEN;
                rctl &= ~IXGB_RCTL_VFE;
        } else {
                if (netdev->flags & IFF_ALLMULTI) {
                        rctl |= IXGB_RCTL_MPE;
                        rctl &= ~IXGB_RCTL_UPE;
                } else {
                        rctl &= ~(IXGB_RCTL_UPE | IXGB_RCTL_MPE);
                }
                /* enable VLAN filtering */
                rctl |= IXGB_RCTL_VFE;
                rctl &= ~IXGB_RCTL_CFIEN;
        }

        if (netdev_mc_count(netdev) > IXGB_MAX_NUM_MULTICAST_ADDRESSES) {
                rctl |= IXGB_RCTL_MPE;
                IXGB_WRITE_REG(hw, RCTL, rctl);
        } else {
                u8 *mta = kmalloc_array(ETH_ALEN,
                                        IXGB_MAX_NUM_MULTICAST_ADDRESSES,
                                        GFP_ATOMIC);
                u8 *addr;
                if (!mta)
                        goto alloc_failed;

                IXGB_WRITE_REG(hw, RCTL, rctl);

                addr = mta;
                netdev_for_each_mc_addr(ha, netdev) {
                        memcpy(addr, ha->addr, ETH_ALEN);
                        addr += ETH_ALEN;
                }

                ixgb_mc_addr_list_update(hw, mta, netdev_mc_count(netdev), 0);
                kfree(mta);
        }

alloc_failed:
        if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX)
                ixgb_vlan_strip_enable(adapter);
        else
                ixgb_vlan_strip_disable(adapter);

}

/**
 * ixgb_watchdog - Timer Call-back
 * @data: pointer to netdev cast into an unsigned long
 **/

static void
ixgb_watchdog(struct timer_list *t)
{
        struct ixgb_adapter *adapter = from_timer(adapter, t, watchdog_timer);
        struct net_device *netdev = adapter->netdev;
        struct ixgb_desc_ring *txdr = &adapter->tx_ring;

        ixgb_check_for_link(&adapter->hw);

        if (ixgb_check_for_bad_link(&adapter->hw)) {
                /* force the reset path */
                netif_stop_queue(netdev);
        }

        if (adapter->hw.link_up) {
                if (!netif_carrier_ok(netdev)) {
                        netdev_info(netdev,
                                    "NIC Link is Up 10 Gbps Full Duplex, Flow Control: %s\n",
                                    (adapter->hw.fc.type == ixgb_fc_full) ?
                                    "RX/TX" :
                                    (adapter->hw.fc.type == ixgb_fc_rx_pause) ?
                                     "RX" :
                                    (adapter->hw.fc.type == ixgb_fc_tx_pause) ?
                                    "TX" : "None");
                        adapter->link_speed = 10000;
                        adapter->link_duplex = FULL_DUPLEX;
                        netif_carrier_on(netdev);
                }
        } else {
                if (netif_carrier_ok(netdev)) {
                        adapter->link_speed = 0;
                        adapter->link_duplex = 0;
                        netdev_info(netdev, "NIC Link is Down\n");
                        netif_carrier_off(netdev);
                }
        }

        ixgb_update_stats(adapter);

        if (!netif_carrier_ok(netdev)) {
                if (IXGB_DESC_UNUSED(txdr) + 1 < txdr->count) {
                        /* We've lost link, so the controller stops DMA,
                         * but we've got queued Tx work that's never going
                         * to get done, so reset controller to flush Tx.
                         * (Do the reset outside of interrupt context). */
                        schedule_work(&adapter->tx_timeout_task);
                        /* return immediately since reset is imminent */
                        return;
                }
        }

        /* Force detection of hung controller every watchdog period */
        adapter->detect_tx_hung = true;

        /* generate an interrupt to force clean up of any stragglers */
        IXGB_WRITE_REG(&adapter->hw, ICS, IXGB_INT_TXDW);

        /* Reset the timer */
        mod_timer(&adapter->watchdog_timer, jiffies + 2 * HZ);
}

#define IXGB_TX_FLAGS_CSUM              0x00000001
#define IXGB_TX_FLAGS_VLAN              0x00000002
#define IXGB_TX_FLAGS_TSO               0x00000004

static int
ixgb_tso(struct ixgb_adapter *adapter, struct sk_buff *skb)
{
        struct ixgb_context_desc *context_desc;
        unsigned int i;
        u8 ipcss, ipcso, tucss, tucso, hdr_len;
        u16 ipcse, tucse, mss;

        if (likely(skb_is_gso(skb))) {
                struct ixgb_buffer *buffer_info;
                struct iphdr *iph;
                int err;

                err = skb_cow_head(skb, 0);
                if (err < 0)
                        return err;

                hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
                mss = skb_shinfo(skb)->gso_size;
                iph = ip_hdr(skb);
                iph->tot_len = 0;
                iph->check = 0;
                tcp_hdr(skb)->check = ~csum_tcpudp_magic(iph->saddr,
                                                         iph->daddr, 0,
                                                         IPPROTO_TCP, 0);
                ipcss = skb_network_offset(skb);
                ipcso = (void *)&(iph->check) - (void *)skb->data;
                ipcse = skb_transport_offset(skb) - 1;
                tucss = skb_transport_offset(skb);
                tucso = (void *)&(tcp_hdr(skb)->check) - (void *)skb->data;
                tucse = 0;

                i = adapter->tx_ring.next_to_use;
                context_desc = IXGB_CONTEXT_DESC(adapter->tx_ring, i);
                buffer_info = &adapter->tx_ring.buffer_info[i];
                WARN_ON(buffer_info->dma != 0);

                context_desc->ipcss = ipcss;
                context_desc->ipcso = ipcso;
                context_desc->ipcse = cpu_to_le16(ipcse);
                context_desc->tucss = tucss;
                context_desc->tucso = tucso;
                context_desc->tucse = cpu_to_le16(tucse);
                context_desc->mss = cpu_to_le16(mss);
                context_desc->hdr_len = hdr_len;
                context_desc->status = 0;
                context_desc->cmd_type_len = cpu_to_le32(
                                                  IXGB_CONTEXT_DESC_TYPE
                                                | IXGB_CONTEXT_DESC_CMD_TSE
                                                | IXGB_CONTEXT_DESC_CMD_IP
                                                | IXGB_CONTEXT_DESC_CMD_TCP
                                                | IXGB_CONTEXT_DESC_CMD_IDE
                                                | (skb->len - (hdr_len)));


                if (++i == adapter->tx_ring.count) i = 0;
                adapter->tx_ring.next_to_use = i;

                return 1;
        }

        return 0;
}

static bool
ixgb_tx_csum(struct ixgb_adapter *adapter, struct sk_buff *skb)
{
        struct ixgb_context_desc *context_desc;
        unsigned int i;
        u8 css, cso;

        if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
                struct ixgb_buffer *buffer_info;
                css = skb_checksum_start_offset(skb);
                cso = css + skb->csum_offset;

                i = adapter->tx_ring.next_to_use;
                context_desc = IXGB_CONTEXT_DESC(adapter->tx_ring, i);
                buffer_info = &adapter->tx_ring.buffer_info[i];
                WARN_ON(buffer_info->dma != 0);

                context_desc->tucss = css;
                context_desc->tucso = cso;
                context_desc->tucse = 0;
                /* zero out any previously existing data in one instruction */
                *(u32 *)&(context_desc->ipcss) = 0;
                context_desc->status = 0;
                context_desc->hdr_len = 0;
                context_desc->mss = 0;
                context_desc->cmd_type_len =
                        cpu_to_le32(IXGB_CONTEXT_DESC_TYPE
                                    | IXGB_TX_DESC_CMD_IDE);

                if (++i == adapter->tx_ring.count) i = 0;
                adapter->tx_ring.next_to_use = i;

                return true;
        }

        return false;
}

#define IXGB_MAX_TXD_PWR        14
#define IXGB_MAX_DATA_PER_TXD   (1<<IXGB_MAX_TXD_PWR)

static int
ixgb_tx_map(struct ixgb_adapter *adapter, struct sk_buff *skb,
            unsigned int first)
{
        struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
        struct pci_dev *pdev = adapter->pdev;
        struct ixgb_buffer *buffer_info;
        int len = skb_headlen(skb);
        unsigned int offset = 0, size, count = 0, i;
        unsigned int mss = skb_shinfo(skb)->gso_size;
        unsigned int nr_frags = skb_shinfo(skb)->nr_frags;
        unsigned int f;

        i = tx_ring->next_to_use;

        while (len) {
                buffer_info = &tx_ring->buffer_info[i];
                size = min(len, IXGB_MAX_DATA_PER_TXD);
                /* Workaround for premature desc write-backs
                 * in TSO mode.  Append 4-byte sentinel desc */
                if (unlikely(mss && !nr_frags && size == len && size > 8))
                        size -= 4;

                buffer_info->length = size;
                WARN_ON(buffer_info->dma != 0);
                buffer_info->time_stamp = jiffies;
                buffer_info->mapped_as_page = false;
                buffer_info->dma = dma_map_single(&pdev->dev,
                                                  skb->data + offset,
                                                  size, DMA_TO_DEVICE);
                if (dma_mapping_error(&pdev->dev, buffer_info->dma))
                        goto dma_error;
                buffer_info->next_to_watch = 0;

                len -= size;
                offset += size;
                count++;
                if (len) {
                        i++;
                        if (i == tx_ring->count)
                                i = 0;
                }
        }

        for (f = 0; f < nr_frags; f++) {
                const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
                len = skb_frag_size(frag);
                offset = 0;

                while (len) {
                        i++;
                        if (i == tx_ring->count)
                                i = 0;

                        buffer_info = &tx_ring->buffer_info[i];
                        size = min(len, IXGB_MAX_DATA_PER_TXD);

                        /* Workaround for premature desc write-backs
                         * in TSO mode.  Append 4-byte sentinel desc */
                        if (unlikely(mss && (f == (nr_frags - 1))
                                     && size == len && size > 8))
                                size -= 4;

                        buffer_info->length = size;
                        buffer_info->time_stamp = jiffies;
                        buffer_info->mapped_as_page = true;
                        buffer_info->dma =
                                skb_frag_dma_map(&pdev->dev, frag, offset, size,
                                                 DMA_TO_DEVICE);
                        if (dma_mapping_error(&pdev->dev, buffer_info->dma))
                                goto dma_error;
                        buffer_info->next_to_watch = 0;

                        len -= size;
                        offset += size;
                        count++;
                }
        }
        tx_ring->buffer_info[i].skb = skb;
        tx_ring->buffer_info[first].next_to_watch = i;

        return count;

dma_error:
        dev_err(&pdev->dev, "TX DMA map failed\n");
        buffer_info->dma = 0;
        if (count)
                count--;

        while (count--) {
                if (i==0)
                        i += tx_ring->count;
                i--;
                buffer_info = &tx_ring->buffer_info[i];
                ixgb_unmap_and_free_tx_resource(adapter, buffer_info);
        }

        return 0;
}

static void
ixgb_tx_queue(struct ixgb_adapter *adapter, int count, int vlan_id,int tx_flags)
{
        struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
        struct ixgb_tx_desc *tx_desc = NULL;
        struct ixgb_buffer *buffer_info;
        u32 cmd_type_len = adapter->tx_cmd_type;
        u8 status = 0;
        u8 popts = 0;
        unsigned int i;

        if (tx_flags & IXGB_TX_FLAGS_TSO) {
                cmd_type_len |= IXGB_TX_DESC_CMD_TSE;
                popts |= (IXGB_TX_DESC_POPTS_IXSM | IXGB_TX_DESC_POPTS_TXSM);
        }

        if (tx_flags & IXGB_TX_FLAGS_CSUM)
                popts |= IXGB_TX_DESC_POPTS_TXSM;

        if (tx_flags & IXGB_TX_FLAGS_VLAN)
                cmd_type_len |= IXGB_TX_DESC_CMD_VLE;

        i = tx_ring->next_to_use;

        while (count--) {
                buffer_info = &tx_ring->buffer_info[i];
                tx_desc = IXGB_TX_DESC(*tx_ring, i);
                tx_desc->buff_addr = cpu_to_le64(buffer_info->dma);
                tx_desc->cmd_type_len =
                        cpu_to_le32(cmd_type_len | buffer_info->length);
                tx_desc->status = status;
                tx_desc->popts = popts;
                tx_desc->vlan = cpu_to_le16(vlan_id);

                if (++i == tx_ring->count) i = 0;
        }

        tx_desc->cmd_type_len |=
                cpu_to_le32(IXGB_TX_DESC_CMD_EOP | IXGB_TX_DESC_CMD_RS);

        /* Force memory writes to complete before letting h/w
         * know there are new descriptors to fetch.  (Only
         * applicable for weak-ordered memory model archs,
         * such as IA-64). */
        wmb();

        tx_ring->next_to_use = i;
        IXGB_WRITE_REG(&adapter->hw, TDT, i);
}

static int __ixgb_maybe_stop_tx(struct net_device *netdev, int size)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;

        netif_stop_queue(netdev);
        /* Herbert's original patch had:
         *  smp_mb__after_netif_stop_queue();
         * but since that doesn't exist yet, just open code it. */
        smp_mb();

        /* We need to check again in a case another CPU has just
         * made room available. */
        if (likely(IXGB_DESC_UNUSED(tx_ring) < size))
                return -EBUSY;

        /* A reprieve! */
        netif_start_queue(netdev);
        ++adapter->restart_queue;
        return 0;
}

static int ixgb_maybe_stop_tx(struct net_device *netdev,
                              struct ixgb_desc_ring *tx_ring, int size)
{
        if (likely(IXGB_DESC_UNUSED(tx_ring) >= size))
                return 0;
        return __ixgb_maybe_stop_tx(netdev, size);
}


/* Tx Descriptors needed, worst case */
#define TXD_USE_COUNT(S) (((S) >> IXGB_MAX_TXD_PWR) + \
                         (((S) & (IXGB_MAX_DATA_PER_TXD - 1)) ? 1 : 0))
#define DESC_NEEDED TXD_USE_COUNT(IXGB_MAX_DATA_PER_TXD) /* skb->date */ + \
        MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE) + 1 /* for context */ \
        + 1 /* one more needed for sentinel TSO workaround */

static netdev_tx_t
ixgb_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        unsigned int first;
        unsigned int tx_flags = 0;
        int vlan_id = 0;
        int count = 0;
        int tso;

        if (test_bit(__IXGB_DOWN, &adapter->flags)) {
                dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        }

        if (skb->len <= 0) {
                dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        }

        if (unlikely(ixgb_maybe_stop_tx(netdev, &adapter->tx_ring,
                     DESC_NEEDED)))
                return NETDEV_TX_BUSY;

        if (skb_vlan_tag_present(skb)) {
                tx_flags |= IXGB_TX_FLAGS_VLAN;
                vlan_id = skb_vlan_tag_get(skb);
        }

        first = adapter->tx_ring.next_to_use;

        tso = ixgb_tso(adapter, skb);
        if (tso < 0) {
                dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        }

        if (likely(tso))
                tx_flags |= IXGB_TX_FLAGS_TSO;
        else if (ixgb_tx_csum(adapter, skb))
                tx_flags |= IXGB_TX_FLAGS_CSUM;

        count = ixgb_tx_map(adapter, skb, first);

        if (count) {
                ixgb_tx_queue(adapter, count, vlan_id, tx_flags);
                /* Make sure there is space in the ring for the next send. */
                ixgb_maybe_stop_tx(netdev, &adapter->tx_ring, DESC_NEEDED);

        } else {
                dev_kfree_skb_any(skb);
                adapter->tx_ring.buffer_info[first].time_stamp = 0;
                adapter->tx_ring.next_to_use = first;
        }

        return NETDEV_TX_OK;
}

/**
 * ixgb_tx_timeout - Respond to a Tx Hang
 * @netdev: network interface device structure
 **/

static void
ixgb_tx_timeout(struct net_device *netdev, unsigned int txqueue)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);

        /* Do the reset outside of interrupt context */
        schedule_work(&adapter->tx_timeout_task);
}

static void
ixgb_tx_timeout_task(struct work_struct *work)
{
        struct ixgb_adapter *adapter =
                container_of(work, struct ixgb_adapter, tx_timeout_task);

        adapter->tx_timeout_count++;
        ixgb_down(adapter, true);
        ixgb_up(adapter);
}

/**
 * ixgb_change_mtu - Change the Maximum Transfer Unit
 * @netdev: network interface device structure
 * @new_mtu: new value for maximum frame size
 *
 * Returns 0 on success, negative on failure
 **/

static int
ixgb_change_mtu(struct net_device *netdev, int new_mtu)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        int max_frame = new_mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;

        if (netif_running(netdev))
                ixgb_down(adapter, true);

        adapter->rx_buffer_len = max_frame + 8; /* + 8 for errata */

        netdev->mtu = new_mtu;

        if (netif_running(netdev))
                ixgb_up(adapter);

        return 0;
}

/**
 * ixgb_update_stats - Update the board statistics counters.
 * @adapter: board private structure
 **/

void
ixgb_update_stats(struct ixgb_adapter *adapter)
{
        struct net_device *netdev = adapter->netdev;
        struct pci_dev *pdev = adapter->pdev;

        /* Prevent stats update while adapter is being reset */
        if (pci_channel_offline(pdev))
                return;

        if ((netdev->flags & IFF_PROMISC) || (netdev->flags & IFF_ALLMULTI) ||
           (netdev_mc_count(netdev) > IXGB_MAX_NUM_MULTICAST_ADDRESSES)) {
                u64 multi = IXGB_READ_REG(&adapter->hw, MPRCL);
                u32 bcast_l = IXGB_READ_REG(&adapter->hw, BPRCL);
                u32 bcast_h = IXGB_READ_REG(&adapter->hw, BPRCH);
                u64 bcast = ((u64)bcast_h << 32) | bcast_l;

                multi |= ((u64)IXGB_READ_REG(&adapter->hw, MPRCH) << 32);
                /* fix up multicast stats by removing broadcasts */
                if (multi >= bcast)
                        multi -= bcast;

                adapter->stats.mprcl += (multi & 0xFFFFFFFF);
                adapter->stats.mprch += (multi >> 32);
                adapter->stats.bprcl += bcast_l;
                adapter->stats.bprch += bcast_h;
        } else {
                adapter->stats.mprcl += IXGB_READ_REG(&adapter->hw, MPRCL);
                adapter->stats.mprch += IXGB_READ_REG(&adapter->hw, MPRCH);
                adapter->stats.bprcl += IXGB_READ_REG(&adapter->hw, BPRCL);
                adapter->stats.bprch += IXGB_READ_REG(&adapter->hw, BPRCH);
        }
        adapter->stats.tprl += IXGB_READ_REG(&adapter->hw, TPRL);
        adapter->stats.tprh += IXGB_READ_REG(&adapter->hw, TPRH);
        adapter->stats.gprcl += IXGB_READ_REG(&adapter->hw, GPRCL);
        adapter->stats.gprch += IXGB_READ_REG(&adapter->hw, GPRCH);
        adapter->stats.uprcl += IXGB_READ_REG(&adapter->hw, UPRCL);
        adapter->stats.uprch += IXGB_READ_REG(&adapter->hw, UPRCH);
        adapter->stats.vprcl += IXGB_READ_REG(&adapter->hw, VPRCL);
        adapter->stats.vprch += IXGB_READ_REG(&adapter->hw, VPRCH);
        adapter->stats.jprcl += IXGB_READ_REG(&adapter->hw, JPRCL);
        adapter->stats.jprch += IXGB_READ_REG(&adapter->hw, JPRCH);
        adapter->stats.gorcl += IXGB_READ_REG(&adapter->hw, GORCL);
        adapter->stats.gorch += IXGB_READ_REG(&adapter->hw, GORCH);
        adapter->stats.torl += IXGB_READ_REG(&adapter->hw, TORL);
        adapter->stats.torh += IXGB_READ_REG(&adapter->hw, TORH);
        adapter->stats.rnbc += IXGB_READ_REG(&adapter->hw, RNBC);
        adapter->stats.ruc += IXGB_READ_REG(&adapter->hw, RUC);
        adapter->stats.roc += IXGB_READ_REG(&adapter->hw, ROC);
        adapter->stats.rlec += IXGB_READ_REG(&adapter->hw, RLEC);
        adapter->stats.crcerrs += IXGB_READ_REG(&adapter->hw, CRCERRS);
        adapter->stats.icbc += IXGB_READ_REG(&adapter->hw, ICBC);
        adapter->stats.ecbc += IXGB_READ_REG(&adapter->hw, ECBC);
        adapter->stats.mpc += IXGB_READ_REG(&adapter->hw, MPC);
        adapter->stats.tptl += IXGB_READ_REG(&adapter->hw, TPTL);
        adapter->stats.tpth += IXGB_READ_REG(&adapter->hw, TPTH);
        adapter->stats.gptcl += IXGB_READ_REG(&adapter->hw, GPTCL);
        adapter->stats.gptch += IXGB_READ_REG(&adapter->hw, GPTCH);
        adapter->stats.bptcl += IXGB_READ_REG(&adapter->hw, BPTCL);
        adapter->stats.bptch += IXGB_READ_REG(&adapter->hw, BPTCH);
        adapter->stats.mptcl += IXGB_READ_REG(&adapter->hw, MPTCL);
        adapter->stats.mptch += IXGB_READ_REG(&adapter->hw, MPTCH);
        adapter->stats.uptcl += IXGB_READ_REG(&adapter->hw, UPTCL);
        adapter->stats.uptch += IXGB_READ_REG(&adapter->hw, UPTCH);
        adapter->stats.vptcl += IXGB_READ_REG(&adapter->hw, VPTCL);
        adapter->stats.vptch += IXGB_READ_REG(&adapter->hw, VPTCH);
        adapter->stats.jptcl += IXGB_READ_REG(&adapter->hw, JPTCL);
        adapter->stats.jptch += IXGB_READ_REG(&adapter->hw, JPTCH);
        adapter->stats.gotcl += IXGB_READ_REG(&adapter->hw, GOTCL);
        adapter->stats.gotch += IXGB_READ_REG(&adapter->hw, GOTCH);
        adapter->stats.totl += IXGB_READ_REG(&adapter->hw, TOTL);
        adapter->stats.toth += IXGB_READ_REG(&adapter->hw, TOTH);
        adapter->stats.dc += IXGB_READ_REG(&adapter->hw, DC);
        adapter->stats.plt64c += IXGB_READ_REG(&adapter->hw, PLT64C);
        adapter->stats.tsctc += IXGB_READ_REG(&adapter->hw, TSCTC);
        adapter->stats.tsctfc += IXGB_READ_REG(&adapter->hw, TSCTFC);
        adapter->stats.ibic += IXGB_READ_REG(&adapter->hw, IBIC);
        adapter->stats.rfc += IXGB_READ_REG(&adapter->hw, RFC);
        adapter->stats.lfc += IXGB_READ_REG(&adapter->hw, LFC);
        adapter->stats.pfrc += IXGB_READ_REG(&adapter->hw, PFRC);
        adapter->stats.pftc += IXGB_READ_REG(&adapter->hw, PFTC);
        adapter->stats.mcfrc += IXGB_READ_REG(&adapter->hw, MCFRC);
        adapter->stats.mcftc += IXGB_READ_REG(&adapter->hw, MCFTC);
        adapter->stats.xonrxc += IXGB_READ_REG(&adapter->hw, XONRXC);
        adapter->stats.xontxc += IXGB_READ_REG(&adapter->hw, XONTXC);
        adapter->stats.xoffrxc += IXGB_READ_REG(&adapter->hw, XOFFRXC);
        adapter->stats.xofftxc += IXGB_READ_REG(&adapter->hw, XOFFTXC);
        adapter->stats.rjc += IXGB_READ_REG(&adapter->hw, RJC);

        /* Fill out the OS statistics structure */

        netdev->stats.rx_packets = adapter->stats.gprcl;
        netdev->stats.tx_packets = adapter->stats.gptcl;
        netdev->stats.rx_bytes = adapter->stats.gorcl;
        netdev->stats.tx_bytes = adapter->stats.gotcl;
        netdev->stats.multicast = adapter->stats.mprcl;
        netdev->stats.collisions = 0;

        /* ignore RLEC as it reports errors for padded (<64bytes) frames
         * with a length in the type/len field */
        netdev->stats.rx_errors =
            /* adapter->stats.rnbc + */ adapter->stats.crcerrs +
            adapter->stats.ruc +
            adapter->stats.roc /*+ adapter->stats.rlec */  +
            adapter->stats.icbc +
            adapter->stats.ecbc + adapter->stats.mpc;

        /* see above
         * netdev->stats.rx_length_errors = adapter->stats.rlec;
         */

        netdev->stats.rx_crc_errors = adapter->stats.crcerrs;
        netdev->stats.rx_fifo_errors = adapter->stats.mpc;
        netdev->stats.rx_missed_errors = adapter->stats.mpc;
        netdev->stats.rx_over_errors = adapter->stats.mpc;

        netdev->stats.tx_errors = 0;
        netdev->stats.rx_frame_errors = 0;
        netdev->stats.tx_aborted_errors = 0;
        netdev->stats.tx_carrier_errors = 0;
        netdev->stats.tx_fifo_errors = 0;
        netdev->stats.tx_heartbeat_errors = 0;
        netdev->stats.tx_window_errors = 0;
}

#define IXGB_MAX_INTR 10
/**
 * ixgb_intr - Interrupt Handler
 * @irq: interrupt number
 * @data: pointer to a network interface device structure
 **/

static irqreturn_t
ixgb_intr(int irq, void *data)
{
        struct net_device *netdev = data;
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        struct ixgb_hw *hw = &adapter->hw;
        u32 icr = IXGB_READ_REG(hw, ICR);

        if (unlikely(!icr))
                return IRQ_NONE;  /* Not our interrupt */

        if (unlikely(icr & (IXGB_INT_RXSEQ | IXGB_INT_LSC)))
                if (!test_bit(__IXGB_DOWN, &adapter->flags))
                        mod_timer(&adapter->watchdog_timer, jiffies);

        if (napi_schedule_prep(&adapter->napi)) {

                /* Disable interrupts and register for poll. The flush
                  of the posted write is intentionally left out.
                */

                IXGB_WRITE_REG(&adapter->hw, IMC, ~0);
                __napi_schedule(&adapter->napi);
        }
        return IRQ_HANDLED;
}

/**
 * ixgb_clean - NAPI Rx polling callback
 * @adapter: board private structure
 **/

static int
ixgb_clean(struct napi_struct *napi, int budget)
{
        struct ixgb_adapter *adapter = container_of(napi, struct ixgb_adapter, napi);
        int work_done = 0;

        ixgb_clean_tx_irq(adapter);
        ixgb_clean_rx_irq(adapter, &work_done, budget);

        /* If budget not fully consumed, exit the polling mode */
        if (work_done < budget) {
                napi_complete_done(napi, work_done);
                if (!test_bit(__IXGB_DOWN, &adapter->flags))
                        ixgb_irq_enable(adapter);
        }

        return work_done;
}

/**
 * ixgb_clean_tx_irq - Reclaim resources after transmit completes
 * @adapter: board private structure
 **/

static bool
ixgb_clean_tx_irq(struct ixgb_adapter *adapter)
{
        struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
        struct net_device *netdev = adapter->netdev;
        struct ixgb_tx_desc *tx_desc, *eop_desc;
        struct ixgb_buffer *buffer_info;
        unsigned int i, eop;
        bool cleaned = false;

        i = tx_ring->next_to_clean;
        eop = tx_ring->buffer_info[i].next_to_watch;
        eop_desc = IXGB_TX_DESC(*tx_ring, eop);

        while (eop_desc->status & IXGB_TX_DESC_STATUS_DD) {

                rmb(); /* read buffer_info after eop_desc */
                for (cleaned = false; !cleaned; ) {
                        tx_desc = IXGB_TX_DESC(*tx_ring, i);
                        buffer_info = &tx_ring->buffer_info[i];

                        if (tx_desc->popts &
                           (IXGB_TX_DESC_POPTS_TXSM |
                            IXGB_TX_DESC_POPTS_IXSM))
                                adapter->hw_csum_tx_good++;

                        ixgb_unmap_and_free_tx_resource(adapter, buffer_info);

                        *(u32 *)&(tx_desc->status) = 0;

                        cleaned = (i == eop);
                        if (++i == tx_ring->count) i = 0;
                }

                eop = tx_ring->buffer_info[i].next_to_watch;
                eop_desc = IXGB_TX_DESC(*tx_ring, eop);
        }

        tx_ring->next_to_clean = i;

        if (unlikely(cleaned && netif_carrier_ok(netdev) &&
                     IXGB_DESC_UNUSED(tx_ring) >= DESC_NEEDED)) {
                /* Make sure that anybody stopping the queue after this
                 * sees the new next_to_clean. */
                smp_mb();

                if (netif_queue_stopped(netdev) &&
                    !(test_bit(__IXGB_DOWN, &adapter->flags))) {
                        netif_wake_queue(netdev);
                        ++adapter->restart_queue;
                }
        }

        if (adapter->detect_tx_hung) {
                /* detect a transmit hang in hardware, this serializes the
                 * check with the clearing of time_stamp and movement of i */
                adapter->detect_tx_hung = false;
                if (tx_ring->buffer_info[eop].time_stamp &&
                   time_after(jiffies, tx_ring->buffer_info[eop].time_stamp + HZ)
                   && !(IXGB_READ_REG(&adapter->hw, STATUS) &
                        IXGB_STATUS_TXOFF)) {
                        /* detected Tx unit hang */
                        netif_err(adapter, drv, adapter->netdev,
                                  "Detected Tx Unit Hang\n"
                                  "  TDH                  <%x>\n"
                                  "  TDT                  <%x>\n"
                                  "  next_to_use          <%x>\n"
                                  "  next_to_clean        <%x>\n"
                                  "buffer_info[next_to_clean]\n"
                                  "  time_stamp           <%lx>\n"
                                  "  next_to_watch        <%x>\n"
                                  "  jiffies              <%lx>\n"
                                  "  next_to_watch.status <%x>\n",
                                  IXGB_READ_REG(&adapter->hw, TDH),
                                  IXGB_READ_REG(&adapter->hw, TDT),
                                  tx_ring->next_to_use,
                                  tx_ring->next_to_clean,
                                  tx_ring->buffer_info[eop].time_stamp,
                                  eop,
                                  jiffies,
                                  eop_desc->status);
                        netif_stop_queue(netdev);
                }
        }

        return cleaned;
}

/**
 * ixgb_rx_checksum - Receive Checksum Offload for 82597.
 * @adapter: board private structure
 * @rx_desc: receive descriptor
 * @sk_buff: socket buffer with received data
 **/

static void
ixgb_rx_checksum(struct ixgb_adapter *adapter,
                 struct ixgb_rx_desc *rx_desc,
                 struct sk_buff *skb)
{
        /* Ignore Checksum bit is set OR
         * TCP Checksum has not been calculated
         */
        if ((rx_desc->status & IXGB_RX_DESC_STATUS_IXSM) ||
           (!(rx_desc->status & IXGB_RX_DESC_STATUS_TCPCS))) {
                skb_checksum_none_assert(skb);
                return;
        }

        /* At this point we know the hardware did the TCP checksum */
        /* now look at the TCP checksum error bit */
        if (rx_desc->errors & IXGB_RX_DESC_ERRORS_TCPE) {
                /* let the stack verify checksum errors */
                skb_checksum_none_assert(skb);
                adapter->hw_csum_rx_error++;
        } else {
                /* TCP checksum is good */
                skb->ip_summed = CHECKSUM_UNNECESSARY;
                adapter->hw_csum_rx_good++;
        }
}

/*
 * this should improve performance for small packets with large amounts
 * of reassembly being done in the stack
 */
static void ixgb_check_copybreak(struct napi_struct *napi,
                                 struct ixgb_buffer *buffer_info,
                                 u32 length, struct sk_buff **skb)
{
        struct sk_buff *new_skb;

        if (length > copybreak)
                return;

        new_skb = napi_alloc_skb(napi, length);
        if (!new_skb)
                return;

        skb_copy_to_linear_data_offset(new_skb, -NET_IP_ALIGN,
                                       (*skb)->data - NET_IP_ALIGN,
                                       length + NET_IP_ALIGN);
        /* save the skb in buffer_info as good */
        buffer_info->skb = *skb;
        *skb = new_skb;
}

/**
 * ixgb_clean_rx_irq - Send received data up the network stack,
 * @adapter: board private structure
 **/

static bool
ixgb_clean_rx_irq(struct ixgb_adapter *adapter, int *work_done, int work_to_do)
{
        struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
        struct net_device *netdev = adapter->netdev;
        struct pci_dev *pdev = adapter->pdev;
        struct ixgb_rx_desc *rx_desc, *next_rxd;
        struct ixgb_buffer *buffer_info, *next_buffer, *next2_buffer;
        u32 length;
        unsigned int i, j;
        int cleaned_count = 0;
        bool cleaned = false;

        i = rx_ring->next_to_clean;
        rx_desc = IXGB_RX_DESC(*rx_ring, i);
        buffer_info = &rx_ring->buffer_info[i];

        while (rx_desc->status & IXGB_RX_DESC_STATUS_DD) {
                struct sk_buff *skb;
                u8 status;

                if (*work_done >= work_to_do)
                        break;

                (*work_done)++;
                rmb();  /* read descriptor and rx_buffer_info after status DD */
                status = rx_desc->status;
                skb = buffer_info->skb;
                buffer_info->skb = NULL;

                prefetch(skb->data - NET_IP_ALIGN);

                if (++i == rx_ring->count)
                        i = 0;
                next_rxd = IXGB_RX_DESC(*rx_ring, i);
                prefetch(next_rxd);

                j = i + 1;
                if (j == rx_ring->count)
                        j = 0;
                next2_buffer = &rx_ring->buffer_info[j];
                prefetch(next2_buffer);

                next_buffer = &rx_ring->buffer_info[i];

                cleaned = true;
                cleaned_count++;

                dma_unmap_single(&pdev->dev,
                                 buffer_info->dma,
                                 buffer_info->length,
                                 DMA_FROM_DEVICE);
                buffer_info->dma = 0;

                length = le16_to_cpu(rx_desc->length);
                rx_desc->length = 0;

                if (unlikely(!(status & IXGB_RX_DESC_STATUS_EOP))) {

                        /* All receives must fit into a single buffer */

                        pr_debug("Receive packet consumed multiple buffers length<%x>\n",
                                 length);

                        dev_kfree_skb_irq(skb);
                        goto rxdesc_done;
                }

                if (unlikely(rx_desc->errors &

                    (IXGB_RX_DESC_ERRORS_CE | IXGB_RX_DESC_ERRORS_SE |
                     IXGB_RX_DESC_ERRORS_P | IXGB_RX_DESC_ERRORS_RXE))) {
                        dev_kfree_skb_irq(skb);
                        goto rxdesc_done;
                }

                ixgb_check_copybreak(&adapter->napi, buffer_info, length, &skb);

                /* Good Receive */
                skb_put(skb, length);

                /* Receive Checksum Offload */
                ixgb_rx_checksum(adapter, rx_desc, skb);

                skb->protocol = eth_type_trans(skb, netdev);
                if (status & IXGB_RX_DESC_STATUS_VP)
                        __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
                                       le16_to_cpu(rx_desc->special));

                netif_receive_skb(skb);

rxdesc_done:
                /* clean up descriptor, might be written over by hw */
                rx_desc->status = 0;

                /* return some buffers to hardware, one at a time is too slow */
                if (unlikely(cleaned_count >= IXGB_RX_BUFFER_WRITE)) {
                        ixgb_alloc_rx_buffers(adapter, cleaned_count);
                        cleaned_count = 0;
                }

                /* use prefetched values */
                rx_desc = next_rxd;
                buffer_info = next_buffer;
        }

        rx_ring->next_to_clean = i;

        cleaned_count = IXGB_DESC_UNUSED(rx_ring);
        if (cleaned_count)
                ixgb_alloc_rx_buffers(adapter, cleaned_count);

        return cleaned;
}

/**
 * ixgb_alloc_rx_buffers - Replace used receive buffers
 * @adapter: address of board private structure
 **/

static void
ixgb_alloc_rx_buffers(struct ixgb_adapter *adapter, int cleaned_count)
{
        struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
        struct net_device *netdev = adapter->netdev;
        struct pci_dev *pdev = adapter->pdev;
        struct ixgb_rx_desc *rx_desc;
        struct ixgb_buffer *buffer_info;
        struct sk_buff *skb;
        unsigned int i;
        long cleancount;

        i = rx_ring->next_to_use;
        buffer_info = &rx_ring->buffer_info[i];
        cleancount = IXGB_DESC_UNUSED(rx_ring);


        /* leave three descriptors unused */
        while (--cleancount > 2 && cleaned_count--) {
                /* recycle! its good for you */
                skb = buffer_info->skb;
                if (skb) {
                        skb_trim(skb, 0);
                        goto map_skb;
                }

                skb = netdev_alloc_skb_ip_align(netdev, adapter->rx_buffer_len);
                if (unlikely(!skb)) {
                        /* Better luck next round */
                        adapter->alloc_rx_buff_failed++;
                        break;
                }

                buffer_info->skb = skb;
                buffer_info->length = adapter->rx_buffer_len;
map_skb:
                buffer_info->dma = dma_map_single(&pdev->dev,
                                                  skb->data,
                                                  adapter->rx_buffer_len,
                                                  DMA_FROM_DEVICE);
                if (dma_mapping_error(&pdev->dev, buffer_info->dma)) {
                        adapter->alloc_rx_buff_failed++;
                        break;
                }

                rx_desc = IXGB_RX_DESC(*rx_ring, i);
                rx_desc->buff_addr = cpu_to_le64(buffer_info->dma);
                /* guarantee DD bit not set now before h/w gets descriptor
                 * this is the rest of the workaround for h/w double
                 * writeback. */
                rx_desc->status = 0;


                if (++i == rx_ring->count)
                        i = 0;
                buffer_info = &rx_ring->buffer_info[i];
        }

        if (likely(rx_ring->next_to_use != i)) {
                rx_ring->next_to_use = i;
                if (unlikely(i-- == 0))
                        i = (rx_ring->count - 1);

                /* Force memory writes to complete before letting h/w
                 * know there are new descriptors to fetch.  (Only
                 * applicable for weak-ordered memory model archs, such
                 * as IA-64). */
                wmb();
                IXGB_WRITE_REG(&adapter->hw, RDT, i);
        }
}

static void
ixgb_vlan_strip_enable(struct ixgb_adapter *adapter)
{
        u32 ctrl;

        /* enable VLAN tag insert/strip */
        ctrl = IXGB_READ_REG(&adapter->hw, CTRL0);
        ctrl |= IXGB_CTRL0_VME;
        IXGB_WRITE_REG(&adapter->hw, CTRL0, ctrl);
}

static void
ixgb_vlan_strip_disable(struct ixgb_adapter *adapter)
{
        u32 ctrl;

        /* disable VLAN tag insert/strip */
        ctrl = IXGB_READ_REG(&adapter->hw, CTRL0);
        ctrl &= ~IXGB_CTRL0_VME;
        IXGB_WRITE_REG(&adapter->hw, CTRL0, ctrl);
}

static int
ixgb_vlan_rx_add_vid(struct net_device *netdev, __be16 proto, u16 vid)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        u32 vfta, index;

        /* add VID to filter table */

        index = (vid >> 5) & 0x7F;
        vfta = IXGB_READ_REG_ARRAY(&adapter->hw, VFTA, index);
        vfta |= (1 << (vid & 0x1F));
        ixgb_write_vfta(&adapter->hw, index, vfta);
        set_bit(vid, adapter->active_vlans);

        return 0;
}

static int
ixgb_vlan_rx_kill_vid(struct net_device *netdev, __be16 proto, u16 vid)
{
        struct ixgb_adapter *adapter = netdev_priv(netdev);
        u32 vfta, index;

        /* remove VID from filter table */

        index = (vid >> 5) & 0x7F;
        vfta = IXGB_READ_REG_ARRAY(&adapter->hw, VFTA, index);
        vfta &= ~(1 << (vid & 0x1F));
        ixgb_write_vfta(&adapter->hw, index, vfta);
        clear_bit(vid, adapter->active_vlans);

        return 0;
}

static void
ixgb_restore_vlan(struct ixgb_adapter *adapter)
{
        u16 vid;

        for_each_set_bit(vid, adapter->active_vlans, VLAN_N_VID)
                ixgb_vlan_rx_add_vid(adapter->netdev, htons(ETH_P_8021Q), vid);
}

/**
 * ixgb_io_error_detected - called when PCI error is detected
 * @pdev:    pointer to pci device with error
 * @state:   pci channel state after error
 *
 * This callback is called by the PCI subsystem whenever
 * a PCI bus error is detected.
 */
static pci_ers_result_t ixgb_io_error_detected(struct pci_dev *pdev,
                                               enum pci_channel_state state)
{
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct ixgb_adapter *adapter = netdev_priv(netdev);

        netif_device_detach(netdev);

        if (state == pci_channel_io_perm_failure)
                return PCI_ERS_RESULT_DISCONNECT;

        if (netif_running(netdev))
                ixgb_down(adapter, true);

        pci_disable_device(pdev);

        /* Request a slot reset. */
        return PCI_ERS_RESULT_NEED_RESET;
}

/**
 * ixgb_io_slot_reset - called after the pci bus has been reset.
 * @pdev    pointer to pci device with error
 *
 * This callback is called after the PCI bus has been reset.
 * Basically, this tries to restart the card from scratch.
 * This is a shortened version of the device probe/discovery code,
 * it resembles the first-half of the ixgb_probe() routine.
 */
static pci_ers_result_t ixgb_io_slot_reset(struct pci_dev *pdev)
{
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct ixgb_adapter *adapter = netdev_priv(netdev);

        if (pci_enable_device(pdev)) {
                netif_err(adapter, probe, adapter->netdev,
                          "Cannot re-enable PCI device after reset\n");
                return PCI_ERS_RESULT_DISCONNECT;
        }

        /* Perform card reset only on one instance of the card */
        if (0 != PCI_FUNC (pdev->devfn))
                return PCI_ERS_RESULT_RECOVERED;

        pci_set_master(pdev);

        netif_carrier_off(netdev);
        netif_stop_queue(netdev);
        ixgb_reset(adapter);

        /* Make sure the EEPROM is good */
        if (!ixgb_validate_eeprom_checksum(&adapter->hw)) {
                netif_err(adapter, probe, adapter->netdev,
                          "After reset, the EEPROM checksum is not valid\n");
                return PCI_ERS_RESULT_DISCONNECT;
        }
        ixgb_get_ee_mac_addr(&adapter->hw, netdev->dev_addr);
        memcpy(netdev->perm_addr, netdev->dev_addr, netdev->addr_len);

        if (!is_valid_ether_addr(netdev->perm_addr)) {
                netif_err(adapter, probe, adapter->netdev,
                          "After reset, invalid MAC address\n");
                return PCI_ERS_RESULT_DISCONNECT;
        }

        return PCI_ERS_RESULT_RECOVERED;
}

/**
 * ixgb_io_resume - called when its OK to resume normal operations
 * @pdev    pointer to pci device with error
 *
 * The error recovery driver tells us that its OK to resume
 * normal operation. Implementation resembles the second-half
 * of the ixgb_probe() routine.
 */
static void ixgb_io_resume(struct pci_dev *pdev)
{
        struct net_device *netdev = pci_get_drvdata(pdev);
        struct ixgb_adapter *adapter = netdev_priv(netdev);

        pci_set_master(pdev);

        if (netif_running(netdev)) {
                if (ixgb_up(adapter)) {
                        pr_err("can't bring device back up after reset\n");
                        return;
                }
        }

        netif_device_attach(netdev);
        mod_timer(&adapter->watchdog_timer, jiffies);
}

/* ixgb_main.c */